Pole width control on plated bevel main pole design of a perpendicular magnetic recording head

ABSTRACT

A main pole layer is deposited within an opening in a patterned photoresist layer on a substrate. The photoresist is thinned to expose an upper portion of a pole tip region that is then trimmed to a rectangular shape while a lower portion retains an inverted trapezoidal shape. Thereafter, a second trimming process forms a pole tip with a first width in the upper rectangular portion and a second thickness and second width which is less than the first width in the lower portion. A CMP step subsequently thins the upper portion to a first thickness of 0.04 to 0.08 microns while the second thickness remains at 0.16 to 0.32 microns. The bottom surface of the lower portion along the ABS becomes the trailing edge in a recording operation. The pole tip has a consistent first width (track width) that is not influenced by CMP process variations.

FIELD OF THE INVENTION

The invention relates to a write pole in a perpendicular magneticrecording head (PMR) and a method for making the same. In particular, awrite pole having a rectangular upper portion and a trapezoidal lowerportion is used to minimize variations in pole width caused by polethickness variations.

BACKGROUND OF THE INVENTION

Perpendicular recording has been developed in part to achieve higherrecording density than is realized with longitudinal recording devices.A PMR write head typically has a main pole with a small surface area atan air bearing surface (ABS) and a flux return pole (opposing pole)which is magnetically coupled to the main pole and has a large surfacearea at the ABS. Critical dimensions of the main pole include a neckheight and a pole width in a pole tip adjacent to the ABS. Magnetic fluxgenerated in the main pole layer passes through the pole tip into amagnetic media and then back to the write head by entering the fluxreturn pole.

A conventional PMR write head 1 is depicted in FIG. 1. The main polelayer 3 is formed on a substrate 2 that may be an Al₂O₃ insulation layerwhich separates the write head from a read head (not shown) in aseparated read/write head. The main pole layer 3 is generally made of amaterial with a high saturation magnetic flux density (Bs) thatterminates in a pole tip also referred to as a write pole 3 a at an ABSwhich is the plane 11-11. There is a first insulation layer 4 on themain pole layer 3 and a second insulation layer 5 on the firstinsulation layer along the ABS. A coil layer 7 is formed on the firstinsulation layer 4 and is coplanar with the second insulation layer 5.Coils within the coil layer 7 are insulated by a third insulation layer8 that may be a photoresist. The third insulation layer 8 and coilsformed therein extend from the second insulation layer 5 to a connectionregion 6 also known as a back gap region that magnetically couples themain pole layer 3 to a flux return pole layer 10. Overlying the coillayer 7 is a fourth insulation layer 9 that separates the coils from theflux return pole.

Referring to FIG. 2, a cross-sectional view of the pole tip 3 a from theplane 11-11 is shown. During a recording operation, the pole tip 3 a andwrite head 1 move over a magnetic recording track (not shown) in the zdirection. The pole tip 3 a usually has an inverted trapezoid shape withsloped sides 21, a top surface 22 that has a pole width (track width) w₁and a bottom surface 20 which has a smaller width than the track width.Each side 21 forms an angle β with the bottom surface. The track widthis typically determined by an ion milling process that removes excessmaterial from the edges of the main pole layer. However, a subsequentchemical mechanical polish (CMP) process that planarizes the main polelayer 3 is difficult to control and a large variation in the resultingmain pole layer thickness may occur. For example, one write head mayhave a pole tip thickness t₁ and track width w₁ following the CMP step.On the other hand, a second write head may have a pole tip thickness t₂and track width w₂ which are smaller than t₁ and w₁, respectively,because of a prolonged CMP process time that forms a top surface 22 c.The thickness difference (t₁−t₂) caused by CMP process variation willhave an adverse impact on device performance since track width andmagnetic flux density delivered by the main pole will vary from onewrite head to the next. Therefore, a method is needed that can produce awrite head which has a more consistent pole width dimension that is notinfluenced by CMP process variations.

Referring to FIG. 3, another concern with a conventional PMR write headduring a recording operation is that the pole tip 3 a tends to becomeskewed at an angle α relative to the recording direction z and themagnitude of α can vary depending on the location of the pole tip on thecircular magnetic recording media. In some cases where the skew angle αis large or where the undercut angle β is significant, undesirablewriting can occur on a track adjacent to the intended recording track.

In U.S. Pat. No. 6,504,675, the slope angle of the pole sides is allowedto be greater than the maximum skew angle in order to suppress the skeweffect. Alternatively, the trailing write pole is comprised of two partsin which a wide trapezoidal section is formed on a narrow rectangularsection that is the leading edge.

A main pole layer with an inverted trapezoidal pole tip is embedded inan inorganic insulation layer in U.S. Pat. No. 6,710,973. A trailingedge, a leading edge, or both lateral edges of the main pole may betapered in a smooth linear or curved fashion.

In U.S. Pat. No. 6,510,024, an upper magnetic pole is trimmed by an ionmilling method in which the incident angle of ion particles iscontrolled to within a range of 65 to 85 degrees. The upper magneticpole has a trapezoidal shape in which a bottom surface nearer anadjoining read head has a greater width than a top surface.

A method for forming a pole tip width less than 1 micron is described inU.S. Pat. No. 5,649,351 in which a photoresist layer that is 5 to 10microns thick is used as an ion milling mask to define a rectangularpole tip in a planar write head. The resulting thin film magnetic writehead is disclosed in U.S. Pat. No. 5,452,164.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a consistent polewidth in a main pole layer of a PMR write head that is not influenced byCMP process variations.

Another objective of the present invention is to provide a pole tipregion in a main pole layer of a PMR write head that has a rectangularupper portion with a leading edge and a bottom portion with an invertedtrapezoidal shape that includes a trailing edge.

A still further objective of the present invention is to provide amethod of forming a main pole layer in a PMR write head according to thefirst two objectives.

According to the present invention, these objectives are achieved in afirst embodiment in which a pole tip is formed in a main pole layer of aPMR write head. The pole tip is one end of a pole tip region that isformed on a substrate and is adjacent to an ABS. The other end isadjacent to a front end portion of the main pole layer. The pole tip andpole tip region are comprised of an upper portion that is a rectangularshape having a first width and a first thickness and a lower portionwhich has an inverted trapezoidal shape having a second thickness. Thebottom surface of the upper portion is coincident with the top surfaceof the lower portion while the bottom surface of the lower portion has asecond width that is less than the first width. The top surface of theupper portion is the leading edge and the bottom surface of the lowerportion is the trailing edge as the pole tip is moved along the ABS in arecording operation. The sides of the upper portion are alignedperpendicular to a substrate while the lower portion has two sides thatintersect the substrate at an angle θ that is about 80 to 85 degrees.

In a second embodiment, the main pole layer is disposed on a bottom yokeand a first insulation layer that have been formed on a substrate. Abottom yoke is formed on the substrate by a conventional method and isrecessed from a first plane that will become an ABS in a subsequent stepwherein the first plane is perpendicular to the substrate. A main polelayer is formed on the bottom yoke by successive steps that involvedepositing a seed layer, patterning a photoresist layer to generate anopening, and depositing the main pole layer in the opening. A keysequence then follows in which the photoresist layer is thinned to acertain thickness below the main pole and a first ion milling process isused to trim an upper portion of the pole tip region to a rectangularshape while the bottom portion adjacent to the photoresist layer retainsan inverted trapezoidal shape. After the photoresist layer is removed bya conventional process, a second ion milling process is performed totrim the pole tip region to a targeted pole width in which the upperportion of the pole tip has a first width that is the track width.Meanwhile, the lower portion of the pole tip region and pole tip retainsits inverted trapezoidal shape. The top surface of the lower portion istrimmed to the first width and the lower surface is trimmed to a secondwidth that is less than the first width. During the second ion millingprocess, exposed portions of the seed layer are removed.

Thereafter, a second insulation layer is deposited on the firstinsulation layer and main pole layer and a CMP step is used to make thesecond insulation layer coplanar with the main pole layer. A write gaplayer is then deposited on the main pole layer and second insulationlayer and a connection area is opened over a back end portion of themain pole layer that will enable a subsequently formed first writeshield to make contact with the main pole layer. A first write shield isformed by selective plating and a portion thereof covers the connectionarea and the write gap layer along the first plane and extends a neckheight distance from the first plane over the pole tip region. Once asecond photoresist layer and underlying seed layer used for theselective plating are removed, a third insulation layer is deposited tofill the opening vacated by stripping the photoresist layer. The thirdinsulation layer and first write shield are planarized simultaneously.The write head is completed by building a second write shield above thefirst write shield and a coil layer above the third insulation layerfollowed by forming a photoresist insulation layer to insulate thecoils, forming a fourth insulation layer on the coil layer and forming athird write shield on the second write shield and fourth insulationlayer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a conventional PMR write headthat has a main pole layer and a flux return pole.

FIG. 2 is a cross-sectional view of the write head in FIG. 1 from theABS plane showing an inverted trapezoidal shape of the pole tip in themain pole layer.

FIG. 3 is a cross-sectional view of the conventional pole tip in FIG. 2that indicates a skew angle in relation to a recording direction.

FIG. 4 is a cross-sectional view from the ABS plane showing theformation of a pole tip region in a main pole layer according to thepresent invention.

FIG. 5 is a cross-sectional view of the pole tip in FIG. 4 after thethickness of an adjacent photoresist layer is reduced according to thepresent invention.

FIG. 6 is a cross-sectional view of the pole tip after an ion millingstep forms an upper rectangular portion.

FIG. 7 is a cross-sectional view of the pole tip in FIG. 6 after theadjacent photoresist layer is removed and a pole trimming step isperformed.

FIG. 8 is a cross-sectional view from the ABS of the pole tip in FIG. 7after an insulation layer is formed coplanar to the main pole layer.

FIG. 9 is a top view that depicts the main pole layer of the presentinvention on a wafer before a lapping process to form an ABS.

FIG. 10 is a cross-sectional view showing the main pole layer in FIG. 9formed on a bottom yoke according to a method of the present invention.

FIGS. 11-13 depict cross-sectional views of successive stages in formingthe PMR write head of the present invention.

FIG. 14 is a top view of the partially formed PMR write head of thepresent invention following the formation of a first write shield.

FIG. 15 is a cross-sectional view from a plane perpendicular to the ABSand FIG. 16 is a cross-sectional view from the ABS of the PMR write headformed according to the present invention.

FIG. 17 is a cross-sectional view showing the magnetic flux path in thePMR write head of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a write pole in a PMR write head for use withmagnetic storage media in a disk drive. A key feature is a main polelayer in which a pole tip region is comprised of an upper rectangularportion and a lower portion with an inverted trapezoidal shape. Theupper portion has a leading edge along an ABS while the lower portionhas a trailing edge in a recording operation. The present invention isalso a method for forming a consistent pole width in a main pole layerthat is not influenced by CMP process variations. The drawings areprovided by way of example and are not intended to limit the scope ofthe invention. Moreover, the elements in the figures are not necessarilydrawn to scale and may have different relative sizes in an actualdevice.

First a method of forming the pole tip according to the presentinvention will be described. Referring to FIG. 4, a cross-sectional viewis shown from a first plane that will subsequently become an ABS asappreciated by those skilled in the art. There is a substrate 29 thatmay be a separation layer made of Al₂O₃ between a read head and a writehead in a separated PMR read-write head, for example. It is understoodthat the substrate may be part of a slider (not shown) formed in anarray of sliders on a wafer. After the write head is completed, thewafer is sliced to form rows of sliders. Each row is typically lapped toafford an ABS before dicing to fabricate individual sliders that areused in a magnetic recording device.

In the exemplary embodiment, a bottom yoke (not shown) which iscomprised of a material such as CoNiFe and recessed a certain distancefrom the first plane is formed on the substrate 29 by a standard processsuch as a sputtering or electroplating method. A first insulation layer30 is formed on the substrate 29 by a physical vapor deposition (PVD) orchemical vapor deposition (CVD) method and may be comprised of Al₂O₃.Next, a planarization step is employed to make the bottom yoke coplanarwith the first insulation layer 30.

In one embodiment, a seed layer 31 such as CoNiFe or CoFeN is sputterdeposited on the first insulation layer 30 and bottom yoke and has athickness of about 500 to 1000 Angstroms. A photoresist layer 32 with athickness of 0.8 to 1.2 microns and preferably 1 micron is patterned onthe seed layer 31 to generate an opening 34 that has a tapered profilein which the top is wider than the bottom. The photoresist layer 32advantageously has a positive tone composition to facilitate asubsequent thinning step. For example, a chemically amplifiedphotoresist (IO362) available from ShinEtsu Chemical Company may be spincoated and baked to form the photoresist layer 32.

The main pole layer which terminates in a pole tip 35 at the first planeis deposited by an electroplating method on the seed layer within theopening 34. Preferably, the top surface 37 of the pole tip (and mainpole layer) is below the top surface 33 of the photoresist layer 32. Thepole tip 35 also has a bottom surface 36 having a width smaller thanthat of the top surface 37. The main pole layer is comprised of amaterial such as CoNiFe or FeCo that has a high saturation magnetic fluxdensity (Bs) and a plated thickness of about 0.7 to 0.9 microns. A moredetailed description of the shape of the main pole layer will beprovided in a later section. It is understood that the pole tip regionextends beyond the first plane (eventual ABS) on the substrate 29 butfor the purpose of this discussion, the fabrication is described withregard to a perspective from the first plane as the write head wouldappear in the final device.

Referring to FIG. 5, a key step is the thinning of the photoresist layer32 to a thickness that is a distance d₁ of about 0.3 to 0.5 micronsbelow the top surface 37 of the pole tip 35 and main pole layer. In oneaspect, the photoresist layer 32 is thinned by first performing ablanket exposure with an appropriate dose that converts the upperportion of the photoresist layer into an aqueous base soluble matrix butdoes not transform the lower portion into an aqueous base solubleregion. Following the exposure, the substrate 30 is treated with anaqueous base developer that removes the upper portion of the photoresistlayer. Alternatively, the photoresist layer 32 may be thinned by areactive ion etch (RIE) or ion milling method that is well known tothose skilled in the art. At this point, the thinned photoresist layer32 a has a top surface 38. Note that each side 39 of the pole tip 35essentially forms a straight edge. It is understood that thecross-sectional shape of the pole tip region is the similar to that ofthe pole tip 35 wherein the top surface 37 is wider than the bottomsurface 36 and sloped sides 39 connect the top and bottom surfaces.Likewise, subsequent processes that modify the sides of the pole tipalso affect the sides (not shown) of the pole tip region in a similarmanner unless otherwise stated.

Referring to FIG. 6, another important step in the method of the presentinvention is a first ion milling step that trims an upper portion of thepole tip 35 which is the region above the top surface 38 of thephotoresist layer 32 a. The upper portion is trimmed to a rectangularshape that has sidewalls 40 which are perpendicular to the substrate 29.As a result, the width of the top surface 37 is reduced but is stillgreater than the width of the bottom surface 36. A bottom portion thatincludes the sidewalls 39 and bottom surface 36 is generally notaffected by the ion milling although the photoresist layer 32 a and topsurface 37 may be thinned by up to 0.1 microns. The distance d₂ betweenthe top surface 37 and the top surface 38 of the photoresist layer 32 aremains at about 0.3 to 0.5 microns. As a result, the upper rectangularportion has a width w of about 0.18 to 0.24 microns. The first ionmilling step may be performed in a process tool from Veeco Company withthe following conditions: a fixture angle of about 10

to 20

and a sweep angle of from 85

to 150

for a period of about 1 to 2 minutes.

Referring to FIG. 7, the photoresist layer 32 a is removed by a wellknown method such as with an organic stripper solution or with oxygenashing. Thereafter, a second ion milling process is performed to furthertrim the pole tip 35 to a targeted width. In one embodiment, the secondion milling step is comprised of a fixture angle of about 40

to 50

and a sweep angle of from 85

to 150

for a period of about 3 minutes. As a result, the top surface 37 istrimmed to a width w₃ of about 0.12 to 0.16 microns which is the trackwidth and the bottom surface 36 is trimmed to a width w₄ of about 0.04to 0.08 microns. The sidewalls 40 of the upper portion remainperpendicular to the substrate 29 and the sidewalls of the lower portionretain a straight edge that forms an angle θ of about 80 to 85 degreeswith a plane 28-28 that is coincident with the bottom surface 36. Theupper portion of the pole tip 35 formed between the sides 40 has athickness d₂ of about 0.16 to 0.32 microns and the lower portion of thepole tip formed between the sidewalls 39 has a thickness c of about 0.16to 0.32 microns wherein the ratio of d₂ to c is from 2:1 to 1:1.Additionally, exposed portions of the seed layer 31 are removed duringthe second ion milling process.

As shown in FIG. 8, a second insulation layer 52 such as Al₂O₃ isdeposited on the first insulation layer 30 and is planarized by a CMPprocess, for instance, to become coplanar with the pole tip 35 and mainpole layer which are thinned to a final thickness of about 0.2 to 0.4microns. Unlike prior art pole tips with an inverted trapezoidal orregular trapezoidal shape, variations in the CMP process do not resultin pole tip width variations. In the pole tip of the present invention,the pole tip 35 will consistently have a pole width w₃ as long as theCMP process does not thin the pole tip below the sides 40 in the upperportion. That is, the upper surface 52 a of the second insulation layeris preferably above the sloped sides 39 of the lower portion of the poletip by a distance d₃ of about 0.04 to 0.08 microns. By maintaining theminimum thickness d₃ of the upper portion to greater than 0.04 microns,erosion of the pole tip below the vertical sidewalls 40 is essentiallyprevented. The thickness of the upper rectangular portion of the poletip in relation to the thickness of the lower inverted trapezoidalportion is represented by the ratio of d₃ to c which is from about0.12:1 to 0.5:1. Another advantage of the present invention is that theupper rectangular portion of the pole tip helps to prevent writing onadjacent tracks when the pole tip becomes skewed during a writeoperation.

Referring to FIG. 9, a top view of the main pole layer 51 is shown on asubstrate before a lapping process that forms a pole tip region with alength NH. During the fabrication process on a wafer, the pole tipregion extends beyond the first plane 60-60 as mentioned previously.Besides a pole tip region 51 a that has a pole width w₃ and a length NH,there is a pole tip region 51 c between the first plane 60-60 and theinitial pole tip 35 that will be removed later in a lapping process. Thepole tip region 51 c will not be shown again in FIGS. 10-17 in order tosimplify the drawings. The main pole layer 51 is also comprised of afront end region formed between the flaired sides 51 f and a back endregion formed between the sides 51 s that are aligned perpendicular tothe first plane 60-60. The sides 5is connect the flared sides 51 f withan end 51 n that typically has a width w₅ of about 10 to 12 microns. Themain pole layer 51 is surrounded on all sides by the second insulationlayer with a top surface 52 a.

Referring to FIG. 10, a cross-sectional view of the partially formedwrite head in FIG. 9 is shown from a plane that is perpendicular to thefirst plane 60-60 and bisects the pole tip region 51 a and end 51 n inthe main pole layer 51. In one embodiment, the bottom yoke 50 isrecessed by a distance y of about 1 micron from the first plane 60-60and the NH dimension of the pole tip region is less than y andpreferably about 0.1 to 0.3 microns.

As shown in FIG. 11, a write gap layer 54 is deposited by a sputteringprocess or the like on the main pole layer 51, pole tip region 51 a, andsecond insulation layer 52 (not shown). The write gap layer 54 may be anAl₂O₃ layer with a thickness of about 500 to 1000 Angstroms andpreferably 800 Angstroms. Next, a second photoresist layer (not shown)is patterned on the write gap layer and an ion beam etch (IBE) isemployed to expose the top surface 51 b of the main pole layer 51 in aso-called connection area within the back end region of the main polelayer. Thereafter, the second photoresist layer is stripped by aconventional method.

Referring to FIG. 12, a seed layer 55 such as CoNiFe is deposited on thewrite gap layer 54 and on the top surface 51 b of the connection area. Aphotoresist layer 56 is patterned on the seed layer 55 and has anopening 53 a above the top surface 51 b of the main pole layer 51 in theconnection area and an opening 53 b that extends a distance TH from thefirst plane 60-60 toward the back end of the main pole layer. The seedlayer 55 is uncovered at the bottom of the openings. Next, a selectiveelectroplating process is performed as is understood by those skilled inthe art which deposits the first write shield 57 on the exposed seedlayer 55 in the openings 53 a, 53 b. The first write shield 57 has athickness of about 1.0 to 1.5 microns and is preferably comprised ofCoNiFe.

Referring to FIG. 13, the photoresist layer 56 is removed by a standardstripping method and then a third insulation layer 58 may be depositedby a CVD or PVD method to fill the opening vacated by the photoresistlayer 56. The third insulation layer 58 may be comprised of Al₂O₃. Thethird insulation layer 58 and first write shield 57 become coplanarafter a planarization step such as a CMP process which reduces the firstwrite shield thickness to about 0.5 microns.

From a top view in FIG. 14, a front portion of the first write shield 57is shown with a front end along the first plane 60-60 and a back endwhich is generally aligned parallel to the first plane except forsegments 57 a on the third insulation layer 58 that may be formed agreater distance than TH from the first plane. The first write shieldalso has a back portion with a rectangular shape formed above the end 51n with the seed layer 55 (not shown) therebetween. However, the backportion does not typically cover the entire end 51 n.

Referring to FIG. 15, the PMR write head is completed by a well knownsequence of steps of which the details are not described herein. In oneembodiment, a second write shield 59 with a similar shape as the firstwrite shield 57 and a thickness of about 2 to 3 microns is formed on thefirst write shield. A front portion of the second write shield 59 alongthe first plane 60-60 has a small overlap of about 0.4 microns on thethird insulation layer 58. Above the third insulation layer 58 notcovered by the second write shield 59 is formed a coil layer 61 thattypically has a spiral shape and is wrapped around the second writeshield on the back end of the main pole layer 51. The coil layer 61 hasa thickness from about 2 to 3 microns and is coplanar with the secondwrite shield 59. Between the coils in the coil layer 59 is a photoresistlayer 62 that serves as an insulation layer. A fourth insulation layer(not shown) which is a 3 to 4 micron thick Al₂O₃ layer is deposited onthe third insulation layer 58 and is planarized by a CMP process untilcoplanar with the second write shield 59. Following the planarizationstep, a fifth insulation layer 63 comprised of Al₂O₃ with a thickness ofabout 0.2 microns is formed on the coil layer 61 and photoresist layer62. A third write shield 64 having a thickness of 2 to 3 microns is thenformed on the fifth insulation layer 63 and on the second write shield59. The third write shield 64 provides a magnetic flux connectionbetween the second write shield 59 along the first plane 60-60 and thesecond write shield over the connection area.

Referring to FIG. 16, a cross-sectional view from the first plane 60-60depicts the write head 70 after a write gap layer 54, seed layer 55,first write shield 57, second write shield 59, and third write shield 64are sequentially formed above the pole tip 35.

The present invention is also the PMR write head depicted in FIGS. 15-17that is fabricated by the previously described method and is comprisedof a main pole layer that has a pole tip region and pole tip having anupper rectangular portion formed on a lower inverted trapezoidalportion. As illustrated in FIG. 15, there is a substrate 29 that may bean Al₂O₃ separation layer in a separated read-write head upon which abottom yoke 50 with a thickness of about 3 microns is formed. The bottomyoke 50 is coplanar with a first insulation layer 30 comprised of Al₂O₃that separates the bottom yoke from a first plane 60-60 which in thiscase is an ABS. The bottom yoke 50 is preferably comprised of CoNiFe andis recessed from the first plane 60-60 by about 1 micron.

A main pole layer 51 is formed on the bottom yoke 50 and firstinsulation layer 30 and has a uniform thickness of about 0.2 to 0.4microns. The main pole layer 51 is coplanar with a second insulationlayer (not shown) disposed on the first insulation layer 30. The mainpole layer 51 and bottom yoke 50 may be comprised of the same magneticmaterial which is CoNiFe or CoFe. A key feature of the main pole layeris the shape of the pole tip 35 pictured in FIG. 8 which has beenpreviously described. The upper rectangular portion has a width w₃ and athickness d₃ while the inverted trapezoidal bottom portion has a widthw₄ less than w₃ and a thickness c wherein the ratio d₃/c is from about0.12:1 to 0.5:1. Sides 40 on the rectangular portion are formed in adirection that is perpendicular to the substrate 32 while sides 39 onthe bottom portion form an angle θ with the plane 28-28 that coincideswith the bottom surface 36.

A write gap layer 54 is disposed on the main pole layer 51, pole tipregion 51 a, and second insulation layer 52. A portion of the back endregion of the main pole layer which serves as a connection area to afirst write shield 57 is not covered by the write gap layer 54. There isa seed layer 55 which may be CoNiFe that extends a distance NH from theABS toward the back end region on the write gap layer 54. The seed layer55 also covers the aforementioned connection area. The first writeshield 57 which is comprised of CoNiFe with a thickness of about 0.5microns has a front portion on the seed layer 55 along the ABS and aback portion on the connection area.

There is a third insulation layer 58 that may be an Al₂O₃ layer which iscoplanar with the first write shield 57 and is formed on the write gaplayer 54 not covered by the first write shield. A second write shield 59is formed on the first write shield 57 and has a thickness of about 2 to3 microns and the same composition as the first write shield. A frontportion of the second write shield along the plane 60-60 extends adistance greater than TH toward the back end of the write head andslightly overlaps the third insulation layer 58. Above the thirdinsulation layer 58 is a coil layer 61 comprised of Cu that is coplanarwith the second write shield 59. Between the coils in the coil layer 61and adjacent to the second write shield 59 is formed a photoresist layer62 that serves as an insulator material. The photoresist layer 62 iscoplanar with the coil layer. There is a fourth insulation layer (notshown) formed adjacent to and coplanar with the second write shield anda fifth insulation layer 63 with a thickness of about 0.2 microns thatcovers the coil layer 61 and photoresist layer 62. The fourth insulationlayer and fifth insulation layer 63 may be comprised of Al₂O₃. The toplayer in the PMR write head of the present invention is a third writeshield 64 that is disposed on the second write shield 59, fourthinsulation layer, and fifth insulation layer 63. The third write shieldis comprised of CoNiFe and has a thickness between 2 and 3 microns.

In FIG. 17, the magnetic flux path of the PMR write head of the presentinvention is illustrated. Only the magnetic layers and first plane 60-60(ABS) are numbered to simply the drawing and direct attention to themagnetic flux direction. Note that the flux return pole is essentiallycomprised of the first write shield 57, second write shield 59, andthird write shield 64. A magnetic flux 71 generated by flowing a currentthrough the coil layer described previously passes through the bottomyoke 50 and main pole layer 51 before a first flux field 71 a exits themain pole layer through the pole tip region 51 a at the pole tip 35 andenters a recording layer 72 and a soft underlayer 73. A second fluxfield 71 b passes from the main pole layer 51 to the first write shieldand then the second write shield before entering the third write shield64. Meanwhile, the first flux field enters the third write shield 64after exiting the recording layer 60. The gap field 71 a enters thethird write gap layer 64 after exiting the recording layer 72. Themagnetic flux path in the third write shield leads to the back end ofthe PMR write head 70 where the magnetic flux 71 transits the secondwrite shield 59 and first write shield 57 (and seed layer 55) in theconnection area to reach the main pole layer 51 and bottom yoke 50 onceagain.

While this invention has been particularly shown and described withreference to, the preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade without departing from the spirit and scope of this invention.

1. A pole tip region in a main pole layer of a PMR write head,comprising: (a) an upper portion having a rectangular shape formedadjacent to an air bearing surface (ABS) wherein the upper portion has afirst width along the ABS and a first thickness; and (b) a lower portionhaving an inverted trapezoidal shape adjacent to the ABS wherein thelower portion has a top surface with a first width, and a bottom surfacewith a second width along the ABS that is less than said first width. 2.The pole tip region of claim 1 wherein said main pole layer is formed ona bottom yoke that is recessed from said ABS.
 3. The pole tip region ofclaim 1 wherein said first width is between about 0.12 and 0.16 microns.4. The pole tip region of claim 1 wherein the first thickness is fromabout 0.04 to 0.08 microns.
 5. The pole tip region of claim 1 whereinthe second thickness is between about 0.16 to 0.32 microns.
 6. The poletip region of claim 1 wherein the second width is about 0.04 to 0.08microns.
 7. The pole tip region of claim 1 wherein the ratio of saidfirst thickness to said second thickness is between about 0.12:1 and0.5:1.
 8. The pole tip region of claim 1 wherein the said lower portionis formed on a substrate and has sidewalls wherein each sidewallintersects said substrate to form an angle of about 80 to 85 degrees. 9.The pole tip region of claim 1 wherein the upper portion includes aleading edge which is the track width in a write operation and thebottom surface of said lower portion is a trailing edge.
 10. A PMR writehead, comprising: (a) a bottom yoke formed on a substrate and separatedfrom an ABS by a first insulation layer; and (b) a main pole layerformed on said bottom yoke and first insulation layer, said main polelayer includes a pole tip region formed adjacent to said ABS wherein thepole tip region is comprised of: (1) an upper portion having arectangular shape with a first width along the ABS and a firstthickness; and (2) a lower portion having an inverted trapezoidal shapewith a second thickness, a top surface with a first width, and a bottomsurface with a second width along the ABS that is less than said firstwidth.
 11. The PMR write head of claim 10 wherein the upper portion hasa leading edge in which the first width is a track width and wherein themain pole layer has a flat upper surface which includes said leadingedge.
 12. The PMR write head of claim 10 wherein said first width isfrom about 0.12 to 0.16 microns.
 13. The PMR write head of claim 10wherein said first thickness is from about 0.04 to 0.08 microns.
 14. ThePMR write head of claim 10 wherein said second thickness is betweenabout 0.16 and 0.32 microns.
 15. The PMR write head of claim 10 whereinsaid second width is from about 0.04 to 0.08 microns.
 16. The PMR writehead of claim 10 wherein the lower portion is formed on said firstinsulation layer and has sidewalls in which each sidewall intersectssaid first insulation layer to form an angle of about 80 to 85 degrees.17. The PMR write head of claim 10 further comprising: (a) a write gaplayer in which a portion thereof is formed on said pole tip region; (b)a front portion of a first write shield formed on said write gap layeralong said ABS and a back portion formed above the main pole layer in aback end region of the PMR write head; (c) a second write shield withfront and back portions formed on the front and back portions,respectively, of the first write shield; (d) a third write shield formedon the second write shield which connects the front and back portionsthereof; and (e) a coil layer formed coplanar with said second writeshield.
 18. The PMR write head of claim 10 wherein the main pole layer,bottom yoke, first write shield, second write shield, and third writeshield are comprised of CoNiFe.
 19. The PMR write head of claim 10wherein the substrate is an Al₂O₃ layer that separates said PMR writehead from a read head.
 20. The PMR write head of claim 17 wherein thefirst write shield, second write shield, and third write shield serve asa flux return pole.
 21. A method of forming a pole tip region in a mainpole layer of a PMR write head, said pole tip region is formed on asubstrate along a first plane that is perpendicular to said substrate,comprising: (a) providing a substrate with a seed layer and a patternedphotoresist layer sequentially formed thereon, said patternedphotoresist layer having a top, bottom, and sloped sidewalls thatexposes portions of the seed layer; (b) depositing a main pole layercomprised of a pole tip region with an inverted trapezoidal shape, a topsurface, and sidewalls on exposed portions of the seed layer; (c)thinning the photoresist layer to a certain distance below the topsurface of said main pole layer and pole tip region to expose thesidewalls in an upper portion of the pole tip region; (d) performing afirst ion milling process to trim the upper portion to a rectangularshape; (e) removing said photoresist layer; (f) performing a second ionmilling process to remove exposed portions of said seed layer and trimsaid main pole layer to provide a pole tip region having an upperrectangular portion with a first width along the first plane and a lowerinverted trapezoidal portion having a second thickness, a top surfacewith a first width, and a bottom surface with a second width less thanthe first width along the first plane; and (g) depositing an insulationlayer on said main pole layer and pole tip region and planarizing theinsulation layer to be coplanar with the main pole layer therebythinning the upper rectangular portion to a first thickness.
 22. Themethod of claim 21 wherein the main pole layer is comprised of CoNiFeand is deposited by an electroplating process to a thickness of about0.7 to 0.9 microns.
 23. The method of claim 21 wherein the patternedphotoresist layer has an initial thickness of about 0.8 to 1.2 micronswhich is thinned to a give a top surface thereof that is about 0.3 to0.5 microns below the top surface of said main pole layer.
 24. Themethod of claim 21 wherein the first ion milling process is comprised ofa fixture angle of about 10° to 20° and a sweep angle of from 85° to150° and is performed for a period of about 1 to 2 minutes.
 25. Themethod of claim 21 wherein the upper rectangular portion after the firstion milling process has a width of about 0.18 to 0.24 microns and athickness of about 0.3 to 0.5 microns.
 26. The method of claim 21wherein the second ion milling process is comprised of a fixture angleof about 40° to 50° and a sweep angle of from 85° to 150° and isperformed for a period of about 3 minutes.
 27. The method of claim 21wherein said first thickness is about 0.04 to 0.08 microns and the firstwidth is from about 0.12 to 0.16 microns.
 28. The method of claim 21wherein the second thickness is between about 0.16 and 0.32 microns andthe second width is from about 0.04 to 0.08 microns.
 29. The method ofclaim 21 wherein the lower inverted trapezoidal portion has slopedsidewalls wherein each sidewall intersects the substrate to form anangle of about 80 to 85 degrees.
 30. The method of claim 21 wherein saidsubstrate is comprised of a bottom yoke and a first insulation layerwhich is coplanar with said bottom yoke wherein said bottom yoke isrecessed by a distance of about 1 micron from said first plane.
 31. Themethod of claim 21 wherein the seed layer is comprised of CoNiFe orCoFeN and said main pole layer is comprised of CoNiFe.
 32. The method ofclaim 21 wherein said patterned photoresist layer is thinned by ablanket exposure to radiation followed by a treatment with an aqueousbase solution.
 33. A method of forming a PMR write head, comprising: (a)forming a bottom yoke on a substrate, said bottom yoke is separated froma first plane that is perpendicular to the substrate by a firstinsulation layer; and (b) forming a main pole layer on said bottom yoke,said main pole layer includes a pole tip region adjacent to said firstplane, comprising: (1) an upper portion having a rectangular shape witha first width along the first plane, a first thickness, and a leadingedge; and (2) a lower portion having an inverted trapezoidal shape witha second thickness, a top surface with a first width, and a bottomsurface which is a trailing edge with a second width along the firstplane that is less than said first width.
 34. The method of claim 33wherein the first width of the upper portion represents the track width.35. The method of claim 33 wherein the first thickness is from about0.04 to 0.08 microns and the first width is between about 0.12 and 0.16microns.
 36. The method of claim 33 wherein the second thickness is fromabout 0.16 to 0.32 microns and the second width is between about 0.04and 0.08 microns.
 37. The method of claim 33 wherein said lower portionis formed on said first insulation layer.
 38. The method of claim 33further comprising: (a) forming a write gap layer in which a portionthereof is disposed on said pole tip region; (b) forming a front portionof a first write shield on said write gap layer along said first planeand a back portion above the main pole layer in a back end region of thePMR write head; (c) forming a second write shield with front and backportions on the front and back portions, respectively, of the firstwrite shield; and (d) forming a third write shield on the second writeshield which connects the front and back portions thereof.
 39. Themethod of claim 33 wherein the main pole layer, bottom yoke, first writeshield, second write shield, and third write shield are comprised ofCoNiFe.
 40. The method of claim 33 wherein the substrate is an Al₂O₃layer that separates said PMR write head from a read head.
 41. Themethod of claim 38 wherein the first write shield, second write shield,and third write shield form the flux return pole of said PMR write head.